The aim of this study is to assess brain and spinal cord atrophy in patients with multiple sclerosis using quantitative MRI study and its relation to clinical disability and psychometric performance.This study was carried out on 30 patients diagnosed as having clinically definite M.S (16 males and 14 females). Their ages ranged between 18-39 years with a mean age of 28.67 + 6.3 years. Patients in this study were subjected to full clinical neurological, clinical disability, clinical neuropsychological and radiological assessment.The results of this study showed that brain atrophy is a hall mark of M.S especially that of secondary progressive type and this atrophy correlate significantly with the degree of physical disability. Cognitive impairment is a common feature of M.S patients especially in those with secondary progressive type. Similarly, cognitive decline correlate well with the physical disability. Lately, a good significant correlation was observed between brain atrophy and cognitive impairment in M.S patients.